"Exist in large numbers" vs "Exist all over"

[kris]

Test No. express/elem-7 "All Agog", question 8

So many good ideas abound in his mind, he finds it difficult to know where to start.

(a) exist all over
(b) exist in large numbers
(c) exist in different parts
(d) exist everywhere

Test No. express/elem-7 "All Agog", answer 8

So many good ideas exist in large numbers in his mind, he finds it difficult to know where to start.

Correct answer: (b) exist in large numbers

Your answer was: incorrect
So many good ideas exist all over in his mind, he finds it difficult to know where to start.
_________________________

please tell me tell "EXIST IN LARGE NUMBERS" is better than "EXIST ALL OVER"?
Does this sentence mean that the person has a lot of ideas in mind?

Thank you
kris

[Torsten]

Yes, the person has a lot of ideas and the correct answer is ideas exist in large numbers.

TOEIC listening, photographs: A grand piano